165
FXUS63 KMQT 300837
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
437 AM EDT Tue Apr 30 2024

.KEY MESSAGES...

- Patchy but locally dense fog diminishes this morning.
- Active pattern continues as a series of low pressure systems
  track across the region into early next week. Above normal
  temps/precip are expected including thunderstorm chances.
- Elevated fire weather conditions are possible over the west
  half of Upper Michigan on Wednesday, but will depend on the
  preceding precipitation.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 436 AM EDT Tue Apr 30 2024

The latest 07Z surface analysis shows a 1006 mb surface low over
Lake Michigamme that is expected to weaken while tracking east-
northeast across Lake Superior today. Nighttime RGB composite
satellite imagery shows an expansive area of low clouds that appears
more scattered across Wisconsin. Surface observations indicate
locally dense fog near Lake Michigan in the vicinity of a subtle
wind shift from SSE to SSW that corresponds to the low
pressure`s cool front. Radar imagery shows an area of rain
showers along and ahead of this front with most of the activity
over Lake Superior. Visibility is improving behind the front
except for the higher elevations of the Copper Country where
webcams show fog/mist supplemented by westerly upslope flow off
Lake Superior.

Overall, expect improving weather conditions today as the low
departs allowing for low clouds to lift and perhaps scatter out this
afternoon. HREF guidance shows decreasing probabilities for low
cloud cover this afternoon and evening across the west half. BUFKIT
analysis suggests low clouds will scatter out at the same time as
mid/high level clouds increase associated with the next system.
Breaks in cloud already apparent on satellite imagery combined with
the time of year (beginning of the stable season) implies skies
clearing more quickly, but it could go either way. Cloudiness is
mostly only relevant to today`s high temps that should be maximized
across the south-central where westerly downslope should give an
extra boost to temps. As is usually the case with light west flow,
convergent lake breezes seem likely across the east this afternoon.
This may result in a few afternoon sprinkles, but measurable
rainfall seems unlikely at this time.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 415 PM EDT Mon Apr 29 2024

Period of active weather continues with a series of low
pressures systems tracking across the area into early next week.
There will be several chances for rain with these systems with
the best chance of widespread moderate rainfall likely occurring
with the system Thursday into Friday as models indicate a feed
of Gulf moisture ahead of it drawing in PWAT values in excess of
an inch.

Starting Tuesday, a mostly dry frontal passage will be moving across
the area tonight, but there may be some sprinkles/drizzle along and
ahead of the front. Model soundings indicate a potential for a few
hours of post-frontal upslope drizzle for the Copper Country Tuesday
morning associated with moisture wrapping around the surface low
tracking north of the area. Otherwise, expect mostly cloudy skies
with highs ranging from the 50s near Lake Superior and east to the
lower to mid 60s interior west and south central.

A vigorous 500 mb shortwave trough approaches from the Northern
Plains Tuesday evening as it becomes negatively tilted and pivots
across the area late Tuesday night into early Wednesday. There`s
very little time for moisture to return ahead of this disturbance
for destabilization and the nocturnal timing further limits thunder
potential. However, there`s very good agreement in convection riding
into the area along the cold front to our west Tuesday afternoon.
These storms appear to grow upscale into an MCS that moves fairly
rapidly across the area late Tue night into early Wed. At this
point, it looks like the best chance for widespread rainfall will be
aligned over the western counties and maybe some of the north
central counties closer to the system`s track and where the better
deep layer qvector convergence and isentropic ascent is fcst. Any
storms that make it into our area should be elevated and shouldn`t
pose a hazard. The window for rainfall is brief (~3 hours) leading
to light rain amounts less than 1/4 inch.

Not great agreement among the models with how much mixing will occur
on the backside of this system on Wednesday afternoon. The GFS
soundings show the potential of mixing to 6-7 kft through a fairly
dry airmass which could drop dew points into the lower 30s (and
perhaps lower) over the interior west with min RHs dipping to 30 pct
or less over the interior west half. Deep mixing off GFS soundings
also suggests westerly gusts could reach near 35 mph. Meanwhile, NAM
soundings depict more clouds with less mixing (only to 3-4 kft)
yielding lesser wind gusts (20 mph or less) and less afternoon
drying of dew points. If the GFS scenario of deeper mixing pans out
the combination of gusty winds and lower RHs could potentially lead
to elevated fire danger, however the recent moderate rainfalls over
the last week could also imply wetter soils/fuels that could limit
the threat.

High pressure builds in Wednesday night resulting in dry conditions,
but then the focus shifts to a low pressure developing over the
Plains on Thursday then tracking across our area Thursday night. As
a result, rain chances increase on Thursday ahead of the warm front
as it lifts north then rain chances end behind Friday`s cold frontal
passage. Ensemble probabilities indicate it`s likely that much of
the area should see QPF totaling a quarter inch or more during this
period with a chance (near 50 pct) of QPF reaching a half inch or
more south central.

Additional generally light rain chances look to continue through
next weekend as weak shortwave impulses continue to move through the
mid-level trough hanging over the area.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 147 AM EDT Tue Apr 30 2024

Slight improvement to MVFR at CMX is expected to be short-lived
early this morning with a return to LIFR/VLIFR when winds shift back
to the west and upsloping returns.  Elsewhere, LIFR cigs remain
steady at IWD and SAW and will continue to do so through mid morning
as moisture wraps around surface low. Anticipate gradual improvement
to MVFR levels from late morning through early afternoon.  But,
confidence becomes low at that point and will trend toward lingering
MVFR for now through the afternoon and into evening hours at all TAF
sites. In addition, westerly winds will be breezy at CMX this
morning with sustained speeds above the 12 kt threshold. An area of
rain with embedded thunderstorms approaches IWD at the end of this
TAF period then CMX/SAW shortly afterward.

&&

.MARINE...
Issued at 415 PM EDT Mon Apr 29 2024

East-northeast gales will quickly fall blo gales late this
afternoon/evening as the sfc low now over northwest WI gradually
lifts over central Lake Superior later tonight and winds become less
than 20 kts. East to southeast winds increase to 20-25 kts Tuesday
night, becoming westerly and increasing to 25-30 kts behind a cold
front on Wednesday. There is now less than 20% chance for westerly
gales up to 35 kts could occur on the windward side of the Keweenaw
shoreline. Winds quickly diminish below 20 kts Wednesday night and
stay light until the next low pressure approaches on Thursday
bringing another episode of gusty easterly to northeasterly winds
Thursday night into Friday with maybe a few low-end gale gusts to 35
kts possible over north central and eastern portions of the lake.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...EK
LONG TERM...Voss
AVIATION...EK/TDUD
MARINE...Voss